Add arg to optionally suppress user segment

This adds the option to common.user to suppress display if the username
matches the given string in the new "hide_user" argument.

powerline/segments/common.py

@@ -591,9 +591,12 @@ username = False
 _geteuid = getattr(os, 'geteuid', lambda: 1)
 
 
-def user(pl, segment_info=None):
+def user(pl, segment_info=None, hide_user=None):
 	'''Return the current user.
 
+	:param str hide_user:
+		will suppress display of username if it matches the given string
+
 	Highlights the user with the ``superuser`` if the effective user ID is 0.
 
 	Highlight groups used: ``superuser`` or ``user``. It is recommended to define all highlight groups.
@@ -604,6 +607,8 @@ def user(pl, segment_info=None):
 	if username is None:
 		pl.warn('Failed to get username')
 		return None
+	if username == hide_user:
+		return None
 	euid = _geteuid()
 	return [{
 		'contents': username,

tests/test_segments.py

@@ -80,6 +80,10 @@ class TestCommon(TestCase):
 						self.assertEqual(common.user(pl=pl, segment_info=segment_info), [
 							{'contents': 'def', 'highlight_group': 'user'}
 						])
+						self.assertEqual(common.user(pl=pl, segment_info=segment_info, hide_user='abc'), [
+							{'contents': 'def', 'highlight_group': 'user'}
+						])
+						self.assertEqual(common.user(pl=pl, segment_info=segment_info, hide_user='def'), None)
 					with replace_attr(common, '_geteuid', lambda: 0):
 						self.assertEqual(common.user(pl=pl, segment_info=segment_info), [
 							{'contents': 'def', 'highlight_group': ['superuser', 'user']}